The effect of inorganic or organic metals and metal complexes is of particular interest because of their prevalence in drinking water and industrial processes, use as constituents in anticancer and antihelminthic drugs, and their diverse target organ toxicities. Toxicological studies of various, selected metallic salts are being conducted to support and extend the results obtained at contract test facilities. Blood and target organ levels are measured to determine the disposition and steady state concentrations of the metal residues. Cellular biochemical responses provided sensitive indices of target organ toxicity that often preceeded clinical signs or microscopic evidence of pathology. Metal salts that have been studied include mercuric chloride, nickel sulfate, and titanocene dichloride. Further studies are underway with sodium chromate, zinc potassium chromate, and chromium carbonyl in female mice to compare the genotoxic and myelotoxic effects of the different hexavalent salts. The effects of 20-day i.p. injections on micronuclei, on bone marrow stem cell proliferation rates, and on cellular biochemistry are being conducted. Studies of the absorption and toxicity of the organoferric salts, ferrocene and ferric ammonium ferrocyanide, are being initiated.